JP2013513241A - Stretched material suitable for use as EMI absorber - Google Patents

Abstract

FIG. 8 is an exemplary embodiment of a method of making an electromagnetic interference (EMI) absorber that extends a material including EMI absorbing particles along at least a first axis to align at least some of the EMI absorbing particles.

Description

  The present disclosure relates to a stretch suitable for use as an EMI absorber.

Although this section provides background information related to the present disclosure, this is not necessarily prior art.
Electronic devices often generate an electromagnetic signal in one part of the electronic device, which may be emitted to another part of the electronic device and disturb this part. This electromagnetic interference (EMI) can degrade or completely eliminate important signals, which can lead to reduced efficiency or inoperability of the electronics. A conductive material (and possibly a magnetic conductive material) may be interposed between the electronic circuit portions to absorb and / or reflect EMI energy to reduce the detrimental effects of EMI. This shield may be in the form of a wall or a complete enclosure, and is placed around the part of the electronic circuit that generates the electromagnetic signal and / or around the part of the electronic circuit that is susceptible to the electromagnetic signal You may For example, electronic circuit or printed circuit board (PCB) components are often sealed with a shield to localize the location of the EMI within its source and to isolate other devices close to the EMI source.

  As used herein, the term electromagnetic interference (EMI) generally includes the emission of both electromagnetic interference (EMI) and radio frequency interference (RFI), and should be considered to refer to both The term "electromagnetic" should generally be considered to include both electromagnetic waves and radio frequencies from external and / or internal sources and also refer to both. Thus, the term shield (as used herein) is generally used to, for example, prevent (or at least reduce) EMI and RFI in and out of the housing or other housing in which the electronic device is placed. , Including both EMI shielding and RFI shielding, and both.

  An object of the present invention is to provide a stretched product suitable for use as an EMI absorbing material.

Although this section provides an overview of the present disclosure, it does not provide a comprehensive disclosure of the full scope or all of the features of the present invention.
An exemplary embodiment of a method of making an electromagnetic interference (EMI) absorber includes stretching a material including EMI absorbing particles along at least a first axis to align at least some of the EMI absorbing particles.

  Another exemplary embodiment includes an electromagnetic interference (EMI) absorber. The absorber comprises a material that is stretched along a first axis and includes an EMI absorbing strip. At least some of the EMI absorbing particles are aligned generally parallel to the first axis.

Other areas of application will be apparent from the description herein. The descriptions and specific examples in this summary are for illustrative purposes only and are not intended to limit the scope of the present disclosure.
The drawings described herein are for the purpose of illustration of selected embodiments only, and are not intended to depict every possible embodiment and are not intended to limit the scope of the present disclosure.

It is a block diagram which shows an example of the preparation methods of an electromagnetic interference wave (EMI) absorber. It is a block diagram which shows another example of the manufacturing method of EMI absorbing material. It is a figure which shows an example of the EMI absorbing piece suspended to matrix material before extending | stretching. It is a figure which shows an example of the EMI absorption piece disperse | distributed to matrix material after extending | stretching.

The examples will now be more fully described with reference to the accompanying drawings.
The EMI absorbing material works to absorb electromagnetic energy (that is, EMI). EMI absorbers convert electromagnetic energy into another form of energy through a process usually referred to as loss. The mechanism of electrical loss includes conduction loss, dielectric loss and magnetic loss. Conduction loss refers to the reduction of EMI by converting electromagnetic energy into thermal energy. The electromagnetic energy induces a current flowing inside the EMI absorber which has a finite conductivity. Due to the finite conductivity, part of the induced current generates heat through the resistor. Dielectric loss refers to the reduction of EMI by converting electromagnetic energy into mechanical displacement of molecules in the absorber with a non-single dielectric constant. Magnetic loss refers to the reduction of EMI by converting electromagnetic energy into rearrangements of magnetic moments in the EMI absorber.

  According to exemplary aspects of the present disclosure, various exemplary embodiments of stretches (films, sheets, three-dimensional objects or articles, etc.) suitable for use as EMI absorbers are provided. For example, one embodiment includes an electromagnetic interference (EMI) absorber extending along a first axis and generally including a material (a matrix material, a sheet, a substrate, etc.) that includes an EMI absorbing piece. At least some of the EMI absorbing particles are aligned generally parallel to the first axis.

  Another exemplary aspect of the present disclosure relates to a method of making an EMI absorber. An exemplary embodiment of a method of making an electromagnetic interference (EMI) absorber comprises stretching a material (matrix material, sheet, substrate, etc.) comprising EMI absorbing particles along at least a first axis to form EMI absorbing particles. Including aligning at least some.

  Referring now to the drawings, FIG. 1 shows an example of a method of producing an EMI absorber (film, sheet, article, three-dimensional object or item, etc.), which is an embodiment of the present disclosure. The above aspect is specifically shown. As shown in FIG. 1, the method includes the step, process or operation 100 of making or forming a sheet from a matrix filled with a filler comprising EMI absorbing strips. The EMI absorbing pieces may be dispersed in the matrix material in a generally random or non-aligned orientation. Alternative embodiments include one or more steps, processes or operations of making or forming a matrix material filled with a filler material including EMI absorbing pieces into a non-sheet three-dimensional article or object. In addition, stretched materials (films, sheets, three-dimensional objects or articles, etc.) may be filled with a filler material containing EMI absorbing pieces by various appropriate processes such as extrusion molding, inflation film molding, stretch blow molding, etc. It may be made or formed from In some embodiments, the EMI absorbing material has a multilayer structure drawn by a sheet extruder or the like. Thus, in such embodiments, the method of making the EMI absorber may generally include stretching of the multilayer structure, such as by a sheet extruder.

  As an example, FIG. 3 shows that the EMI absorbing pieces 300 dispersed in the matrix material 302 are not aligned. For this particular embodiment illustrated, the EMI absorber is in the form of an elongated foil. Some embodiments may include EMI absorbing strips with aspect ratios ranging from about 10 to about 140. EMI absorbing strips having an aspect ratio of less than 10 or more than 140 may be used. In other embodiments, the aspect ratio of all of the EMI absorbing strips may be about 10, and in other embodiments, the aspect ratio of all of the EMI absorbing strips may be about 140. In further embodiments, the size of the EMI absorbing strips may vary, and each EMI absorbing strip need not be the same size or the same aspect ratio as the other EMI absorbing strips. As used herein, the aspect ratio can be calculated as the ratio of the long (x) dimension to the short (y) dimension, and the x and y dimensions are substantially in the general plane. Perpendicular to Additional embodiments may also include EMI absorbers having one or more of granules, spheroids, microspheres, ellipsoids, irregular spheroids, strands, powders, and / or some or all of their forms. Good.

  Continuing with FIG. 1, the method includes the steps of substantially aligning at least some of the EMI absorbing strips, such as for stretching the sheet along at least a first axis and using it more effectively. Or operation 102 is also included. In some embodiments, the sheet can be extruded or drawn, such as by drawing the sheet to roll between a pair of rollers. In some embodiments, the majority (eg, about 20% to about 70%) of the EMI absorbing strips are aligned after being stretched in step, process or operation 102. In certain embodiments, 70% of the flakes align after stretching, in other embodiments 20% of the flakes align after stretching, and in other embodiments, 70% or more of the flakes align after stretching, and others In an embodiment, less than 20% of the flakes align after stretching.

  While the method of this particular example illustrated in FIG. 1 describes forming and stretching a sheet, alternative embodiments may include extruded objects and articles other than a sheet. For example, another exemplary method may include the step, process or operation of extruding into a non-sheet three-dimensional article or object after mixing the matrix material and the EMI absorbing material. Furthermore, some embodiments may include other processes to make stretches (such as films, three-dimensional objects or articles) suitable for use as EMI absorbers. As an example, other exemplary methods may include inflation film forming, stretch blow molding, and the like.

  As an example, FIG. 4 shows the EMI absorbing strip 400 after stretching, wherein at least some of the EMI absorbing strips 400 are generally aligned in an end-to-end relationship. As shown in contrast to FIG. 3 and FIG. 4, this stretching causes at least some of the EMI absorbing strips to shift in the longitudinal direction and to be oriented in the longitudinal direction, thereby The length or longitudinal axis is generally parallel to an axis 404 along which the sheet is stretched.

  In addition to stretching along a first axis (e.g., axis 404 shown in FIG. 4), some embodiments stretch the sheet or other along a second axis to provide EMI absorbing strips May be included or aligned. Thus, in some embodiments, the sheet or otherwise may extend in a single axial direction along only the first axis (stretching in either the X or Y direction only). On the other hand, in other embodiments, the sheet or other may be stretched in two axial directions (stretched in the X and Y directions) along both the first axis and the second axis.

  Depending on the particular embodiment and the material used for the matrix material and the EMI absorber, for example, a sheet or the like, and in some embodiments about 5% stretching to about 100% stretching is achieved As such, it may extend in a single axial direction only along the first axis. As an example, a sheet or the like may be stretched in a single axial direction, less than 5% in some embodiments, about 5% in some embodiments, along only the first axis. Stretching, 5% or more but less than 50% stretching in some embodiments, about 50% stretching in some embodiments, about 100% stretching in some embodiments, 100% in some embodiments The above stretching may be achieved. In these examples, 100% stretching refers to stretching of a sheet or the like, and the length and / or width (for example, 2 mm) of the finished stretched product or product being the first original before stretching, respectively. Refers to twice the length or width (eg, 1 millimeter).

  Alternatively, for example, the sheet or the like may be stretched along two axial directions to achieve a stretch of about 5% to about 100% in the X and / or Y directions. As an example, a sheet or other may be stretched in two axial directions, less than 5% stretched in some embodiments, about 5% in some embodiments, along the X and / or Y axes. Stretching, 5% or more but less than 50% stretching in some embodiments, about 50% stretching in some embodiments, about 100% stretching in some embodiments, 100% in some embodiments The above stretching may be achieved. In these examples, 100% stretching refers to stretching of a sheet or the like, and the length and / or width (for example, 2 mm) of the finished stretched product or product being the first original before stretching, respectively. Refers to twice the length or width (eg, 1 millimeter).

  As an example, the sheet may be simultaneously stretched along the first axis and the second axis. Alternatively, for example, the sheet may be stretched sequentially along the first axis and the second axis. That is, the sheet may be stretched first along the first axis and then the sheet may be stretched along the second axis (or vice versa). Further, according to a particular embodiment, the sheet may be repeatedly stretched along either the first and / or second axis.

  In various embodiments, the first and second axes along which the sheet is stretched may be substantially perpendicular to one another. In such an embodiment, the first axis may be oriented generally parallel to the longitudinal axis or the longitudinal direction of the sheet, and the second axis may be oriented generally parallel to the transverse axis or the widthwise direction of the sheet. .

  A variety of EMI absorbing particles, fillers, flakes, etc. (referred to as microwave absorbing particles, fillers, flakes, etc.) may be used in the exemplary embodiments of the present disclosure. EMI (or microwave) absorbing particles, fillers, flakes, etc. may be made of various conductive and / or magnetic materials. By way of example, various embodiments include carbonyl iron, sendust (an alloy comprising about 85% iron, about 9.5% silicon and about 5.5% aluminum), permalloy (about 20% iron and about 80% nickel) Alloy), iron silicide, iron chromium compound, metallic silver, magnetic alloy, magnetic powder, magnetic flake, magnetic particle, nickel-based alloy and powder, chromium alloy, and EMI absorbing particle having one or more of combinations thereof May be included. Other embodiments may include one or more EMI absorbing particles formed from one or more of the above materials, wherein the EMI absorbing particles are granules, spheroids, microspheres, ellipsoids, irregular spheroids, strands And / or flakes, powders, and / or one or more combinations of some or all of these forms. In such embodiments, the sheet or the like may also be stretched along one or more axes, which may eliminate gaps and / or reduce space between EMI absorbing particles. And help reduce the through-thickness (z-direction thickness) of the resulting EMI absorber (eg, sheet, film, object, three-dimensional object or item, etc.). Conversely, this improves the properties of the EMI absorption or EMI absorbing particles so that the use of EMI absorbing particles can be reduced (thereby reducing the material cost) while still having sufficient EMI absorbing properties. You can keep it.

  Various exemplary embodiments may include individual EMI absorbing strips, eg, having an average thickness of about 0.1 micrometers (μm) to 1.0 μm. Each EMI absorbing piece has a surface having, for example, an average area represented by square μm and an average thickness represented by μm, and the average area is about 1000 to 7000 times larger than the average thickness. An example of an EMI absorbing piece is manufactured by Steward Advanced Materials (www.stewardmaterials.com) and is called "Iron Silicide Type IV (type IV iron silicide)". In this example, the thickness of the foil is about 0.1 μm to 0.3 μm, and the diameter of the flat surface of the foil is about 20 μm to 30 μm. Alternate embodiments may include different sizes of EMI absorbing particles in a different configuration. The dimensions described in this paragraph (as well as all dimensions disclosed herein) are for illustrative purposes only and are not intended to be limiting.

  In some embodiments, the EMI absorbing piece comprises a magnetic material such that the relative permeability is greater than 2 at 1.0 megahertz. In a particular embodiment, the EMI absorbing piece has a relative permeability of greater than about 3.0 at about 1.0 gigahertz and greater than about 1.5 at 10 gigahertz. Alternate embodiments may include different sizes of EMI absorbers with different configurations. These particular numbers listed in this paragraph (as well as all numbers disclosed herein) are for illustrative purposes only and not for limitation.

  A variety of materials can be used for the matrix material. By way of example, various embodiments include polyolefins, polyamides, polyesters, polyurethanes, polycarbonates, polystyrenes and styrenic copolymers, acrylonitriles, polyvinyl chlorides, polysulfones, acetals, polyarylates, polypropylenes, Surlyns, polyethylene terephthalates. And thermoplastic matrix materials such as polystyrene and combinations thereof.

  The matrix material may be selected based on a specific amount of EMI absorbing strip that may be dispersed or added to the matrix material. For example, some embodiments may have a volume (e.g., 15 to 40 volumes) of EMI absorber that does not interfere with other advantageous properties of the matrix material, such as the ability to stretch and maintain the alignment of the EMI absorber after stretching. Percent, less than 15% by volume, 40% by volume or more) can be received, and can contain a dispersible matrix material.

  The matrix material may be substantially transparent to electromagnetic energy such that the matrix material does not interfere with the absorption of the EMI absorbing fillers (such as flakes) that occur therein. For example, a matrix material having a dielectric constant less than about 4 and a loss tangent less than about 0.1 is sufficiently permeable to EMI. However, values outside of this range may also be considered, and these specific numbers described in this paragraph (same as those disclosed herein) are for illustrative purposes only and for purposes of limitation. It is not something to do.

  FIG. 2 is a flowchart illustrating steps, processes or operations in another exemplary method of the present disclosure. As shown in FIG. 2, the method includes the step, process or operation 200 of mixing the matrix material and the EMI absorbing strip, and extruded into a sheet at this step, process or operation 202. This particular example includes an extruded sheet. Alternative embodiments may include extruded objects and articles other than sheets or films. For example, another exemplary method may include the step, process or operation of mixing the matrix material and the EMI absorbing material and then extruding it into a three-dimensional article, article or object that is not a sheet or film. In addition, some embodiments may include other processes to make stretches (eg, films, sheets, three-dimensional objects or articles, etc.) suitable for use as EMI absorbers. As an example, other exemplary methods may include inflation film forming, stretch blow molding, and the like. In some embodiments, the EMI absorbing material has a multilayer structure drawn by a sheet extruder or the like. Thus, in these embodiments, the method of making the EMI absorber may generally include stretching of the multilayer structure, such as by a sheet extruder.

  Continuing with FIG. 2, the sheet is poured into a cooling drum and the sheet is solidified in a step, process or operation 204. The sheet is heated to the draw temperature in step, process or operation 206. The sheet is then stretched, eg, longitudinally, in a step, process or operation 208. Additionally or alternatively, the sheet may be stretched, for example, in a cross direction, in a step, process or operation 210. Implementing biaxial stretching along two axes in the X and Y directions can be done sequentially or simultaneously as already mentioned. In the step, process or operation 212, the stretched sheet can be rolled or spooled, for example for transport or storage.

  For this particular method shown in FIG. 2, the matrix material and the EMI absorber may comprise the various materials listed above. In certain exemplary embodiments, the matrix material and the EMI absorbing material include a flaky iron silicide filler by this method to form a stretched thermoplastic sheet, the filler comprising a step, process or operation 208, 210. As a result of being stretched, they are selected to be substantially aligned. By aligning the iron silicide flakes, the EMI absorption rate can be improved, so it is possible to reduce the EMI absorbing filling material used (thereby reducing the cost) while still obtaining sufficient EMI absorption. .

  As described above, FIG. 3 shows the EMI absorbing pieces 300 dispersed in the matrix material 302 before stretching, so the flakes 300 are not aligned as a whole, but are randomly dispersed in the matrix material 302. There is. In contrast, FIG. 4 shows the flakes 400 and matrix material 402 after stretching along the first axis 402 so that some of the flakes 400 are substantially aligned along the axis 402. By stretching and aligning the slices in this way, it is possible to remove the gaps between the slices and / or reduce the space, and also to obtain the obtained EMI absorber (eg film, sheet, object, It will help to reduce the penetration thickness of the three-dimensional goods or objects etc), ie the thickness in the z direction (which is on the page of FIG. 4). Conversely, this can reduce the amount of these EMI absorbers used (and thereby reduce material costs) to help improve the EMI absorption properties or absorption of the flakes, while sufficient EMI. The absorption properties can still be maintained.

  The relative sizes of the individual EMI absorbing strips 300, 400 with respect to each other and with the matrix material 302, 402 are shown in FIGS. 3 and 4, which are for illustration purposes only. In general, the dispersed EMI absorbers may be very small (ie, microscope size). Due to the small particle size of the filler, the overall thickness can be relatively thin in the EMI absorbing sheet embodiment.

  Likewise, the relative shape of the EMI absorbing strips or particles may be any arbitrary shape. Elongated EMI absorbing strips 300, 400 are shown in FIGS. 3 and 4, which are for illustration purposes only. Other embodiments may include one or more EMI absorbing strips or particles of different shapes than those shown in FIGS. 3 and 4. For example, various embodiments of the EMI absorbing material include oriented sheets (sheets stretched along the first and / or second axes), as well as granules, spheroids, microspheres, ellipsoids, irregular spheroids, strands , One or more EMI absorbing fillers or particles having flakes, powders, and / or some or all combinations of these forms. In such embodiments, the sheet can still be stretched along one or more axes, this stretching can eliminate the gaps between the EMI absorbing particles and / or help reduce the space, and It also helps to reduce the through thickness, i.e. the thickness in the z-direction, of the resulting EMI absorbing material (e.g. sheet, film, object, three-dimensional object or item etc). Conversely, this improves the EMI absorption properties or absorption rate of the EMI absorbing particles, so that the amount of use of these EMI absorbing particles can be reduced (thereby reducing the material cost) while sufficient EMI absorption can be achieved. The characteristics can still be kept.

  In operation, an EMI absorber (eg, film, sheet, object, three-dimensional object or item, etc.) according to the exemplary embodiments disclosed herein is adapted to absorb a portion of EMI incident on the EMI absorber. Operate, thereby reducing EMI propagation through the EMI absorber beyond the operable frequency range (eg, a frequency range of about 10 gigahertz or more, such as about 100 megahertz to about 1 gigahertz, etc.) be able to. The EMI absorber can remove some of the EMI from the in-situ environment due to the power dissipation caused by the loss mechanism. Such loss mechanisms include polarization loss in dielectric and conductive or ohmic materials, loss in conductive materials with finite conductivity, and the like.

  The EMI absorbing material (eg, film, sheet, article, three-dimensional object or article, etc.) may further include an adhesive layer. In some embodiments, the adhesive layer is formed using a pressure sensitive adhesive. Pressure sensitive adhesives (PSAs) may generally be based on compounds including acrylics, silicones, rubbers and combinations thereof. The adhesive layer adheres EMI absorbing material to a part of the EMI shield, such as one EMI shield, cover, lid, frame, or other parts of multiple shields, and the separate EMI shield wall It can be used for Alternative application methods such as mechanical fasteners may also be used. In some embodiments, an EMI absorber (eg, film, sheet, etc.) may be attached to the removable lid or the cover of multiple EMI shields. The EMI absorbing material may, for example, be located on the inner surface of the cover or lid. Alternatively, the EMI absorber may be located, for example, on the outer surface of the cover or lid. The EMI absorbing material may be placed on the entire surface or less than the entire surface of the cover or lid. For example, the EMI absorber may be set on the frame or base, and another EMI absorber may be placed on the lid or cover attached to the frame or base. The EMI absorber can be applied to virtually any location where it is desired to install the EMI absorber.

  In one or more of the various embodiments disclosed herein, an EMI absorber (eg, film, sheet, etc.) may be attached to the frame and shield including the cover attachable to the frame. For example, the cover may include a detent for securing the cover to a frame mounted to the circuit board. The cover may be pressed down perpendicularly to the frame and the cover may be engaged with the frame by engaging and locking at least one locking snap in the corresponding opening. In some embodiments, the cover is a locking snap or catch (eg, a latch, a tab, etc.) having a frame that includes an opening (eg, a recess, a gap, a cavity, a slot, a slot, a slot, a hole, a combination thereof, etc.). Detents, protrusions, protrusions, ribs, bumps, upslopes, darts, lances, recesses, semi-recesses, combinations thereof and the like). In another embodiment, the frame includes a locking snap or catch and the cover includes a corresponding opening. In yet another embodiment, the cover and frame may both include locking snaps or catches that engage corresponding openings in other parts.

In some embodiments, the EMI absorbing material may be formed as a tape. This tape can be wound and stored, for example, on a roll.
In some embodiments, the EMI absorbing material can be die cut into desired application shapes, such as rectangles and ovals, which can result in any desired two-dimensional shaped EMI absorbing material. Therefore, the EMI absorbing material can be die-cut to obtain an application shape having a desired outer shape.

  In some embodiments, the EMI absorber may have a better thermal conductivity than air without a thermally conductive filler. However, in some embodiments, a thermally conductive filler may be included in the matrix along with the EMI absorbing particles (such as flakes). In such embodiments, the resulting thermally conductive EMI absorbing material can be used as a thermally conductive EMI absorbing material, for example, between an electronic component (eg, a "chip") and a heat sink. A variety of thermally conductive fillers (eg, ceramic materials, aluminum nitride, boron nitride, iron, metal oxides, and combinations thereof) may be used, for which the value of the thermal impedance is substantially Also included are thermally conductive fillers smaller than air. As an example, various embodiments of the EMI absorbing material (eg, film, sheet, article, three-dimensional object or article, etc.) may include EMI absorbing particles (eg, flakes) and a thermally conductive filler in a matrix In this matrix, the EMI absorbing material is stretched along at least a first and / or a second axis.

  The examples are provided so that this disclosure will be thorough enough, and will fully convey the scope of the invention to those skilled in the art. Numerous specific details are described as examples of specific parts, devices and methods to provide a thorough understanding of the disclosed embodiments. It will be apparent to those skilled in the art that it is not necessary to use specific details, that the examples may be implemented in many different forms, and that nothing should be construed as limiting the scope of the present disclosure. I will. In some embodiments, known processes, known device structures, and known techniques are not described in detail.

  The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms "a", "an" and "the" are intended to include the plural as well, unless the context clearly indicates otherwise. The terms "comprises", "comprising", "including" and "having" are intended to be inclusive and thus the described features, integers, steps To identify the presence of an operation, element, and / or component, but exclude the presence or addition of one or more other features, numbers, steps, operations, elements, components and / or groups thereof Absent. The steps, processes and operations of the present method described herein are not to be construed as necessarily requiring implementation in the specific order described or illustrated unless specifically specified as the order of execution. It should also be understood that additional or alternative steps may be used. Moreover, the steps, processes or operations used herein should not be limited to only those steps, processes or operations involving only a single act. Conversely, a step, process or operation as used herein may refer to a single act or more than one act.

  As used herein, the terms first, second, third, etc. may be used to describe various elements, components, regions, layers and / or sections, but these elements, components, regions, Layers and / or compartments should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Terms such as “first”, “second” and other terms used in the present specification do not imply order or order unless the context clearly indicates otherwise. As such, the first element, component, region, layer or section described below may be referred to as a second element, component, region, layer or section without departing from the teachings of the example.

  The disclosure of values and ranges of values for particular parameters (temperature, molecular weight, weight percent, etc.) does not exclude other values and ranges of values available herein. It is expected that two or more specific values exemplified for a given parameter will be defined as the endpoints of the range of values that can be claimed for this parameter. For example, in the present specification, if the value of parameter X is illustrated as being A and the value is illustrated as being Z, it is expected that the range of values of parameter X may be from about A to about Z . Similarly, if we disclose more than one range of values for a parameter (whether such ranges are nested, overlapping or separate), The disclosure is expected to cover all possible combinations of ranges for the value that can be claimed using the endpoints of the disclosed range. For example, if it is exemplified herein that the value of the range of parameter X is 1-10, or 2-9, or 3-8, the value of parameter X is 1-9, 1-8, 1 It is also expected that other ranges may be included such as -3, 1-2, 2-10, 2-8, 2-3, 3-10, and 3-9.

  The foregoing description of the embodiments has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention. Individual elements or features of a particular embodiment are not limited to the particular embodiment throughout, but may be interchanged with one another as needed, even if not specifically illustrated or described. It can be used in the embodiment described above. Also, individual elements or features of particular embodiments may vary. Such variations are not to be regarded as a departure from the invention, and all such modifications are intended to be included within the scope of the invention.

Claims (30)

  A method of making an electromagnetic interference (EMI) absorber, comprising stretching a material comprising EMI absorbing particles along at least a first axis to align at least some of the EMI absorbing particles.   The method of claim 1, further comprising: stretching the material along a second axis.   The method of claim 2, wherein the second axis is substantially perpendicular to the first axis.   3. The method of claim 2, wherein the material is stretched along the first axis and simultaneously stretching the material along the second axis.   The method of claim 1, wherein the material comprises EMI absorbing particles dispersed in a matrix material.   6. The method of claim 5, further comprising dispersing the EMI absorbing particles in the matrix material prior to stretching.   7. A method according to any one of the preceding claims, wherein the material comprises a sheet and the stretching comprises stretching the sheet at least along the first axis.   8. The method of claim 7, further comprising forming the sheet from the EMI absorbing particles dispersed in the matrix material.   Stretching the material comprising the EMI absorbing particles reduces the space between the EMI absorbing particles, helps to reduce the penetration thickness of the material, and the stretched comprising the EMI absorbing particles 7. A method according to any one of the preceding claims, characterized in that at least one of improving the EMI absorption properties of the material.   The method according to any one of claims 1 to 6, wherein the stretching aligns the longitudinal direction of at least some of the EMI absorbing particles substantially parallel to the first axis.   The EMI absorbing particles include one or more of granules, spheroids, microspheres, ellipsoids, irregular spheroids, strands, flakes, powders, and some or all of their shapes in combination. A method according to any one of the preceding claims.   The method according to any one of the preceding claims, characterized in that the material comprises at least one of a thermoplastic sheet and the EMI absorbing particles comprise iron silicide flakes.   A method according to any one of the preceding claims, wherein the material comprises a thermoplastic matrix filled with iron silicide flakes.   The method according to any one of claims 1 to 6, wherein the EMI absorbing particle comprises one or more of carbonyl iron, sendust, permalloy, iron silicide and iron chromium compound. The EMI absorbing particles comprise flakes, at least some of the individual flakes being
An average thickness of about 0.1 μm to 1.0 μm,
That the aspect ratio is in the range of about 10 to about 140,
The average area of the surface is expressed in square μm, the average thickness is expressed in μm, and the average area is about 1000 to 7000 times larger than the average thickness, and the magnetic permeability is more than 2 at 1.0 MHz. about,
7. A method according to any one of the preceding claims, characterized in at least one of the following.   7. A method according to any one of the preceding claims, further comprising attaching the stretched material comprising the EMI absorbing particles to a part of an EMI shielding device.   An EMI absorber produced by the method according to any one of claims 1 to 6.   The EMI absorption film produced by the method as described in any one of Claims 1 thru | or 6.   An electromagnetic interference (EMI) absorber comprising: a material extending along at least a first axis and comprising EMI absorbing particles, wherein at least some of the absorbing particles are aligned substantially parallel to the first axis.   20. The EMI absorber of claim 19, wherein the material comprises a sheet stretched along the first axis and the second axis.   The EMI absorber of claim 20, wherein the second axis is substantially perpendicular to the first axis.   The EMI absorbing material according to any one of claims 19 to 21, wherein the material comprises a matrix material filled with the EMI absorbing particles.   22. Any one of claims 19 to 21 characterized in that the matrix material comprises a thermoplastic matrix material, and the EMI absorbing particles comprise an EMI absorbing piece dispersed in the thermoplastic matrix material. EMI absorber as described in 1 or 2.   The EMI absorbing material according to any one of claims 19 to 21, wherein the material comprises a sheet containing the EMI absorbing particles.   22. The EMI absorber according to any one of claims 19 to 21, wherein the EMI absorbing particle comprises a flake whose entire length is aligned substantially parallel to the first axis.   22. The EMI absorbing particle according to any one of claims 19 to 21, wherein the EMI absorbing particle comprises at least one of granules, spheroids, microspheres, ellipsoids, irregular spheroids, strands, flakes, powders, and some or all of their shapes. EMI absorber as described in any one of the above.   22. The EMI absorbing material according to any one of claims 19 to 21, wherein the EMI absorbing particle contains one or more of carbonyl iron, sendust, permalloy, iron silicide and iron chromium compound. The EMI absorbing particles comprise flakes, at least some of the individual flakes being
An average thickness of about 0.1 μm to 1.0 μm,
That the aspect ratio is in the range of about 10 to about 140,
The average area of the surface is expressed in square μm, the average thickness is expressed in μm, and the average area is about 1000 to 7000 times larger than the average thickness, and the magnetic permeability is more than 2 at 1.0 MHz. about,
22. The EMI absorber according to any one of claims 19 to 21, characterized by at least one of the following.   The EMI absorber according to any one of claims 19 to 21, wherein the EMI absorber is a film.   An electromagnetic interference (EMI) shield apparatus having a portion to which the EMI absorbing material according to any one of claims 19 to 21 is attached.